An engine may include deactivating cylinders to improve fuel economy. The engine's cylinders may be deactivated from time to time at lower engine loads, and the cylinders may be reactivated in response to an increase in driver demand torque. The driver demand torque may increase and decrease with traffic conditions. Consequently, it may be possible for the engine to enter and exit cylinder deactivation as frequently as the driver changes a position of the vehicle's accelerator pedal. One way to reduce the busyness of cylinder mode changes is to enter cylinder deactivation at one engine torque request level and exit cylinder deactivation at a different engine torque request level. However, if the engine torque request changes are relatively large, the engine may still change cylinder modes as fast as the driver applies and releases the accelerator pedal. Consequently, the driver may notice the cylinder mode changes and find them objectionable. Further, the frequent cylinder mode changes may increase engine fuel consumption instead of saving fuel.
The inventors herein have recognized the above-mentioned disadvantages and have developed an engine operating method, comprising: adjusting a time a first cylinder poppet valve is allowed to be deactivated via a controller in response to an amount of time a second cylinder poppet valve was deactivated during a prior period of cylinder deactivation; and deactivating the first cylinder poppet valve via the controller in response to the time the first cylinder poppet valve is allowed to be deactivated.
By tracking an amount of time a cylinder is deactivated and basing deactivation of another cylinder based on the amount of time, it may be possible to provide the technical result of reducing cylinder mode change busyness. For example, if a valve is deactivated for a long period of time, a subsequent request to deactivate engine cylinders may be acted upon sooner since the likelihood of the cylinders remaining deactivated may be high. Further, if the cylinder was deactivated for only a short period of time, other cylinders may be delayed from being deactivated but not locked out of being deactivated. In this way, cylinder mode busyness may be managed without having to lock out cylinder deactivation. As a result, cylinder mode change busyness and engine fuel consumption may be reduced.
The present description may provide several advantages. For example, the approach may reduce cylinder mode change busyness. Further, the approach may improve engine fuel economy by reducing the possibility of entering cylinder deactivation without reactivating the cylinders before the amount of fuel consumed by the cylinder mode change is saved via operating the engine with fewer cylinders. Additionally, the approach may eliminate the need to lock cylinders out of deactivation modes.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.